Understanding the Plantar Reflex (or Babinski Sign)

A question that comes up frequently in our EMT class is, “How do we assess distal motor function in altered or unconscious patients?” It’s a fair question. We usually drill our EMT students on checking that distal neuro function before and after c-spine immobilization. You remember the drill, “Can you squeeze my hands? Can you push down with your feet?” But how do we check motor function when the patient can’t or won’t respond to our requests?

One helpful assessment tool is the test for plantar flexion. This is sometimes referred to as the Babinski reflex although, the Babinski reflex is actually a little different than a simple plantar reflex. Both are useful to understand, so lets talk about them.

1) Plantar Reflex

If you’re ticklish on the bottom of your feet, you’re familiar with the Plantar reflex. That uncontrollable urge that some people have to move and jerk when an external stimuli is scraped up the bottom of their foot is rooted in the body’s plantar reflex. While this reflex can be illicited from both conscious and unconscious patients, it becomes particularly helpful in our unconscious subjects (when our other motor assessment options are limited).

To evaluate the plantar reflex, take a blunt, somewhat pointed object and run it up the medial aspect of the underside of the foot. (I prefer the business end of a pair of tightly closed trauma shears.) The movement should start at the heal and end up somewhere in the neighborhood of the little piggy that had roast beef…or even the little piggy that had none.

In the normal adult patient, the toes should point downward and inward and the foot should flex (point).

A strong plantar flexion movement indicates normal motor-neuro function in that leg. If the patient’s reflex is delayed, sluggish or absent, it should be noted for further examination. A sluggish plantar reflex may indicate neurological depression from sedation or an underlying disease process and an absent reflex may indicate some degree of neurological insult (head or spine injury).

One other abnormal finding that the caregiver should watch for is the extension of the toes (fanning out) and an extension of the top of the foot toward the head (dorsiflexion). This is an abnormal finding that is known as…

2) Babinski Sign

When the foot and toes abnormally extend upward toward the head during a plantar reflex assessment, this is called Babinski sign or Babinski reflex. It can be benign. Sleeping adults and children under two tend to have Babinski sign with no underlying pathology. But it is also present in head injury and some degrees of spinal cord injury.

If your patient has a suspected head or neck injury, checking for plantar reflex and noting the normal or abnormal results is certainly worth adding to your patient assessment toolbox.

Now it’s your turn: Do you use the plantar reflex assessment in your patient assessments? How well does it work? Leave us a comment and let us know.

@Mike Thanks for the study Mike. Interesting findings. I guess I’m not seeing the correlation between this study and your advice to simply not use the Babinski test. The test showed a 56% correlation between the known weakness of the test subject and the evaluation of the physician. Why would you not use a test that identifies weakness over 50% of the time? Like most of our physical assessments, the presence of a Babinski reflex doesn’t rule out weakness.

The motion of plantar stimulation as well as the interpretation of the responses, are very specific. A true Babinski response involves dorsiflexion of the big toe, with or without fanning of the other toes…AND flexion of the hip joint simultaneously. If the plantar stimulation is performed incorrectly, one can elicit plantar flexion easier than the intended response. Working with a neurologist for a few years taught me this.

I was diagnosed with M.E. many years ago. It’s been very severe. Recently I experienced a few hours of unexplained paralysis. A neurologist said he didn’t know what caused it. I have been comparing M.E. with M.S. symptoms? He did say that my left plantar reflex was unresponsive, I was just wondering what that means? Thanks

Hi, with regards to the research by “Mike” and the subsequent questions about why 50% indication isn’t heeded; Genuine question; isn’t a 50% success rate in giving a correct indication useless? Might we not be as well off flipping a coin as using something with only 56% success rate? Okay so it’s slightly better than coin flipping, 6% to be exact, but surely for something to be scientifically viable it should have a success rate of close to 90% at the very least?

Good question Laura. It isn’t anything like flipping a coin because it is an abnormality. Once you find it, your diagnosis becomes very specific. If only %50 percent of people who have a neurologic issue have this sign and 50% of people who Do Not have a neurological issue also have this sign…then you would be flipping a coin. But it is an abnormal finding. That’s what makes it valuable.

Here is an example. Lets say you are wandering around at a crowded fair. There are thousands of people present. And I told you that I wanted you to find my father. You would immediately ask me, “Well Steve, what does your father look like? So lets say I could tell you that %56 of the time he wears a blue shirt. This could be helpful, but only if blue shirts are normally uncommon. Do you see where I’m going with this? If nobody ever wore a blue shirt to the fair, suddenly, the fact that my father wears a blue shirt %56 of the time would be very useful information. IF everyone wears a blue shirt %56 of the time…the information is useless. We would be “flipping a coin”.

Normal folks don’t have absent Babinski reflex. Almost everyone has an active Babinski sign. Knowing that %56 of patients with an active neurological deficit will have an abnormal Babinski sign is very useful information. It’s the blue shirt in the crowd. One you do find it you say to yourself, “Hey wait, I need to look closer at this” And you start looking for other signs. Physical assessments don’t exist in a vacuum. They go along with a complete clinical picture.

Everything I read about the Babinski sign seems doom-ridden, with everywhere saying presentation of it past age 2 is open of a list of scary things to deal with. I would be pleased to know it can present in an adult who is quite healthy/normal.

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when is plantar reflex used? only on patients who have suffered a spinal cord injury?
sorry and I was also wondering, why the babinski response was present when motor pathways are altered or disrupted?

my girl is 2 years and 2 months, I was curious about this test so I performed the test several times on her while she was sleeping…I interpreted it as a positive sign because, her big toe dorsiflexed and the other toes fanned out. Being that she was sleeping and she just turned 2 years old, what are the chances that the findings were incorrect/premature?